iSCSI configuration

[fatticus]

Hello,

I have been reading a lot about iSCSI lately so i decided to give it a try. I am runing FreeNAS 8.3.1 and have created iSCSI targets for mounting on ESXi 5.1. I have been running NFS + ZFS for about a year and had no issues however i am bored and wanted to do some benchmarks comparing the two.

Currently i have iSCSI + UFS (i heard ZFS requires lots of tweaking to run properly with iSCSI)

My question is how to do proper configuration on this, currently i have created a target for each VM that i have (5 of them) all with 100GB extents. Is it better to simply make 1 target using all of the UFS disk space and make say a 1TB extent and mount this in ESXi, then simply create the VM's off that datastore?

Backups, with UFS what is the best way to backup my extents / targets? should i just use ZFS, make the tweaks and use snap shots, saving the snap shots on a separate volume?

Can i just backup the extent? when i was using ZFS + NFS i could simply backup the directory the ESXi created for the VM, move it around all i wanted and was always able to import it back into esxi. with iSCSI how would i do that? backup the extent? then import when needed.

Little confused on the iSCSI stuff in regards to backups, and can not seem to find much in here via search function.

any info would be appreciated.

Thanks!

 

[cyberjock]

My question is how to do proper configuration on this, currently i have created a target for each VM that i have (5 of them) all with 100GB extents. Is it better to simply make 1 target using all of the UFS disk space and make say a 1TB extent and mount this in ESXi, then simply create the VM's off that datastore?

That depends on your own knowledge, experience, etc. You can do either one. Each has it's own pluses and minuses so you need to choose based on YOUR needs.

Backups, with UFS what is the best way to backup my extents / targets? should i just use ZFS, make the tweaks and use snap shots, saving the snap shots on a separate volume?

Again, that depends. Some people do stuff like use Acronis and backup the iSCSI device when its mounted to a workstation.

And don't assume that you can "make the tweaks" and it'll "just work". Using iSCSI on ZFS can range anything from no zfs tuning needed to months of painstaking testing. And if your iSCSI devices are constantly being disconnected from your server you may have data corruption. That's why UFS is recommended for iSCSI or just give up on iSCSI altogether. I view iSCSI as one of those things that can work well in very very specific situations and that's all. Too many people want to avoid using a hard drive and go to iSCSI. Well, there's a reason why many iSCSI devices are 5 figure.

When friends ask for advice for using iSCSI I tell them to save themselves the hassle and buy a hard drive. It's amazing to me how many people will spend hours and hours trying to get iSCSI to work for them when they could have spent $50 on a hard drive and saved themselves countless hours of pain both during setup and later when there were issues.

Can i just backup the extent? when i was using ZFS + NFS i could simply backup the directory the ESXi created for the VM, move it around all i wanted and was always able to import it back into esxi. with iSCSI how would i do that? backup the extent? then import when needed.

Little confused on the iSCSI stuff in regards to backups, and can not seem to find much in here via search function.

I don't have any advice on that because its something that is more of a personal decision on how you want your backups to work. It's not a question for FreeNAS users as its not really a FreeNAS problem. It's a problem left to he admin to decide how to handle. I'd Google around and see what all the options are and which one you like the most.

 

[fatticus]

Sweet, thanks for the reply cyberjock.

Ill defiantly keep goggling around to find some more info specific to my situation, but thanks for clearing some stuff up for me.

The reason i didn't go with local disks and chose ZFS + NFS to begin with was that my ESXi datastore would utilize the benefits of raidZ1 ( redundancy, snap shots etc). From what i understand (again this is more of ESXi forum stuff) ESXi raids are only reliable if you had a hardware raid card which is not going to happen due to cost. Also i have noticed i see faster response times with iSCSI but i think that would be due to the fact it is UFS not ZFS, having only 8GB of memory likely played a role there.

I think im going to get more memory and go back to ZFS + NFS, like you said iSCSI seems to be more hassle than its worth so far and i don't see any major benefits to it other than learning a bit about SAN functionality.

Thanks again!

 

[cyberjock]

Sweet, thanks for the reply cyberjock.

Ill defiantly keep goggling around to find some more info specific to my situation, but thanks for clearing some stuff up for me.

I dunno. I thought my answer was more of "keep searching if you want answers". So I'm not sure if I cleared up anything except to maybe convince you that iSCSI is a PITA to setup and use.

 

[fatticus]

convince you that iSCSI is a PITA to setup and use.

It is looking this way haha. Just thought I would see what all the iSCSI talk was about ...

 

[jgreco]

An IBM ServeRAID M1015 in IR mode is a good entry-level RAID controller for ESXi, only about $75 on eBay. The M5015 is a version with cache and when paired with BBU is hard to beat for low cost reasonably fast ESXi RAID storage.